Valve is now in action after warning community server hosts about players who is using modded weapon skills.
Valve started to ban community servers which don't apply the developer's rules. If you falsify your inventory content be careful, Valve is watching. At first, some users started to complain about that they are banned, some of them has no idea that the weapons skins are not allowed.
It is clear that Valve is not okay with modes that provide you weapon skills. Brian Lev made an explanation about this:
Innovation is awesome and almost every mod we see is fine. Our only concern, as the community correctly understands, is with mods that specifically misrepresent a player's skill group/rank or the items they own.For more detailed information, you can visit Game Server Operation Guidelines.